Download Metamorphic Rocks Meta – Change Morphic - Form

Metamorphic Rocks
Meta – Change
Morphic - Form
Metamorphic rocks are formed beneath the Earths surface (usually deeper than 5
miles). Metamorphism is a process which brings about physical and/or chemical
changes in a rock due to extreme pressure, high temperature, or exposure to
chemically active fluids. The change to the rock occurs while the rock is solid, not
liquid.
The deeper a rock is buried, the
higher the pressure, and the
higher the temperature.
Metamorphic rock texture:
Foliation – A layering or banding effect in some metamorophic rocks. Caused by
the parallel alignment of minerals, due to high pressure.
Names are based on whether the rock is foliated, the degree of metamorphism,
and the parent rock.
2 Foliated rocks:
1) Gneiss – a coarse grained,
foliated metamorphic rock, containing
large minerals. Parent rocks are often
granite, gabbro, conglomerate.
If the parent rock is discernable, name
the rock with its parent rock as an
adjective. e.g. Granite gneiss
2) Schist – a medium grained rock, usually with flaky, shiny minerals
present.
Non-foliated metamorphic rocks:
Slate – a very fine grained rock, resulting from a low grade metamorphism of shale.
The appearance of slate is shinier than shale, and is used to make blackboards,
pool tables, roofing, tile,..
Slate Quarry in Pennsylvania
Quartzite – Formed from the metamorphism of
quartz rich sandstone. Can be any color, and
will be very hard. Quartzite is a very durable
rock, which is used frequently for tile and
countertops.
Marble – Formed from the metamorphism of limestone. Can be coarse to fine
grained, and many colors. Will fizz with acid, since it is made of the mineral
calcite.
Migmatite – This is a rock that has partially melted, then solidified. It will have
both igneous and metamorphic rocks within it.